Off-page optimization is organizing backlinks from other sites to your own site. You want to have a mix of different kinds of links, not all one type. The anchor text, the description inside the hyperlink, shouldn’t mention the targeted keyword for the page/post too often to avoid getting penalized for overoptimized links. It’s a commonplace to use the URL of the page, the name of the site, and other non-related anchor text to have a blended backlink profile. Doing so avoids getting penalized by Google and others. You also want to avoid having low-quality links that could get your site into trouble later.
MOZ.com has their Domain Authority and Page Authority metrics which work logarithmically and determine their feeling about how the domain and a given page as rated by Google. The rating runs from 0 to 100 and sometimes can be unrated too. Anything above a 50 is considered extremely highly rated, with 30 being quite respectable and 20 being still decent.
A backlink is a link from another place on the internet to your site. You can receive links from within a Slideshare slide, a blog post, the description below a YouTube video, a Web 2.0 site, and other places. Backlinks from sites with a similar topic to your site tend to be valued more highly. Links from older sites with a higher Domain Authority or Page Authority also help with ranking better.
Link prospecting is all about trying to get links from another web site to your own. This can be done various ways such as offering a guest post for free on another site in exchange for a link from the post published on the other site back to your own. Publishing an infographic and offering it for publication elsewhere often delivers several links where people cite the source of the infographic.
Link building needs to appear to be organic and not forced. Paying for links is frequently done, but risks the integrity of the site when doing so. Acquiring links from a public network that clearly sells links is likely to cause problems down the road when Google hits the public network.
A link is stronger if it’s a link from one site to your own and doesn’t have a reciprocal link from your site back to theirs too. Links can be do follow or no follow, with the no follow ones not passing any link juice with them. Link juice boosts your site when a powerful, respected site links to a less respected one.